Coupled natural convection and radiation in a cubic cavity filled with an air-H2O mixture in the presence of a heated obstacle

Natural convection in a cubical cavity with a hot obstacle located on its floor is investigated. The inner fluid is a semi-transparent mixture of dry air and water vapour, which creates a coupled convective and radiative transport within the fluid. The conservation equations are solved by a finite volume method and the radiative transfer equation by using the discrete ordinates method. The radiative properties of the mixture are accounted for by a spectral line weighted sum of grey gases model associated to the rank correlated approach. It was observed that the volume radiation has a strong influence on the thermal and dynamic fields. The nearly vertical stratification of the temperature field around the plume is broken. Radiation also accelerates the boundary layers near the lateral surfaces and the ceiling and the floor of the enclosure. The total heat transfer is decreased due to both the reduction in convective process near the vertical walls and the attenuation by radiation.